An easy, quantitative method for detection of endonuclease activity

An easy yet sensitive assay has been developed for the detection of endonuclease activities. The method involves the use of agarose gel electrophoresis to resolve intact homogeneous nucleic acid substrate from degradation products resulting from a small number of nucleolytic breaks. The assay is quantitative when a radioactively labeled nucleic acid is used as substrate, and it is as sensitive in the measurement of nuclease activity as is zone sedimentation in sucrose gradients. The assay can detect as few as 1.4 nicks, on the average, per substrate molecule. Its advantage over previous methods of analysis is the ease with which large numbers of samples can be handled while still retaining a high degree of sensitivity. The method is demonstrated with single-stranded DNA substrate, but it can be easily modified to detect endonuclease degradation of double-stranded DNA or degradation of RNA substrate.